The present invention relates to a chuck brake for use with a reversible drill, particularly of the hand-held, reversible, variable speed electric type.
As is well known, portable electric drills are quite often provided with a drill chuck or so-called chuck having a housing which is relatively rotatable with respect to a chucking element for tightening and loosening. For accomplishing such relative rotation, the chuck housing is typically provided with gear teeth around a peripheral forward portion thereof. The drill chuck typically has apertures into one of which a chuck key may be inserted for rotation, the chuck key having gear teeth which mesh with those of the chuck housing for imparting the relative rotation of the housing and chucking element.
Chucks of tools of this character are often used for holding a variety of different devices, including the shanks of drill bits, as well as accessories such as grinding wheels, sanding disks and so forth.
It is a great waste of time and an inconvenience as well for the user to have to resort to above-described operation of the chuck key for tightening or loosening the drill chuck, particularly where one desires to quickly and promptly change drill bits or other accessories which are to be chucked by the drill chuck.
One could simply provide some sort of device for locking the chuck housing to prevent its movement whereupon, when the tool is energized, the drill chuck would be caused to rotate relative to the drill chuck housing which would remain immobile. This would indeed cause tightening of the drill chuck about the shank of the drill bit or other accessory when the drill is operated in the forward direction. However, as tightening occurs, the electric motor of the tool becomes locked. This can result in overheating and even melting of the windings of the motor commutator. To prevent such possibility, it is desired that the motor be allowed to turn when full power is developed.
It might be supposed that one could simply use one's hand to apply friction to the chuck housing for tightening or untightening the chuck by operating the drill. However, under no circumstances should this be attempted, as it produces friction burns and can result in wrenching or even breaking one's wrist. In any event, the attempted use of the hand applies insufficient friction for satisfactory tightening or loosening of the chuck.
Accordingly, it is an object of the invention to provide a brake for the chuck of a reversible drill tool.
A further object of the invention is the provision of such a chuck brake which is manually operable for selectively frictionally impeding rotation of a chuck housing of such a chuck to permit selective tightening of a drill chuck of the chuck about the shank of a drill bit or other shanked device.
Another object of the invention is the provision of such a chuck brake which is selectively manually operable for frictionally impeding rotation of the chuck housing in an opposite direction for loosening of the drill chuck from about the shank of a drill bit or other shanked device.
A still further object of the invention is the provision of such a chuck brake which is selectively manually operable to provide increased friction for use in frictionally impeding rotation of the chuck housing in the opposite direction more greatly than in the forward direction, thereby to facilitate and assure loosening of the drill chuck.
Yet another object of the invention is the provision of such a chuck brake selectively manually operable to cause operation of the drill with reverse rotation to be automatically enabled without further effort by the user.
A further object of the invention is the provision of such a chuck brake which is selectively manually operable for frictionally impeding the rotation of the chuck housing without locking the chuck housing from rotation, thereby to prevent a motor of such a drill from being stalled when fully energized, hence preventing damage to the motor.
A still further object of the invention is the provision of such a chuck brake which allows sufficient friction to be entirely safely applied to the chuck housing for fully satisfactory tightening or loosening of the chuck.
Among other objects of the invention may be noted the provision of such a chuck brake which is not only of a relatively simple and easily assembled construction but which also is low in cost, reliable in operation, and of a most durable character.
Additional objects will be in part apparent and in part pointed out hereinafter.